US4137476A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermionic cathode
Assignee: Denka Co Ltd
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Filing: 1977-05-18
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Granted: 1979-01-30
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Expires: 1997-05-18
Abstract
Abstract A thermionic cathode for an electron beam device is provided which comprises a first layer of thermoelectron emissive compound sharpened towards a point, a third layer of metal of high melting point and a second layer of reaction barrier interposed between the first and third layers, current terminals being attached to said third layer. According to the invention, a thermionic cathode capable of emitting stable electron beams of high intensity for a long period of time can be manufactured.
Inventors
- 👤 Masaji Ishii
- 👤 Shuzo Watanabe
- 👤 Akira Miyai
- 👤 Hideo Hiraoka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:49
CPC Classifications
H; H01; H01J; H01J1/00; H01J1/02; H01J1/13
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
112 words
A thermionic cathode for an electron beam device which comprises a first layer of a single thermoelectron emissive compound sharpened towards a point, a third layer of metal of high melting point and a second layer of reaction barrier material interposed between the first and third layers, said reaction barrier material being selected from one or more of the group consisting of borides and nitrides having high melting points and electrically conducting properties, a first current terminal being directly welded to said third layer and a second current terminal being directly welded to said third layer whereby electric current passes from the first terminal through said third layer to the second terminal.
Claim 2
Dependent Claim
112 words
A thermionic cathode for an electron beam device which comprises a first layer of a single thermoelectron emissive compound sharpened towards a point, a third layer of metal of high melting point and a second layer of reaction barrier material interposed between the first and third layers, said reaction barrier material being selected from one or more of the group consisting of borides and nitrides having high melting points and electrically conducting properties, a first current terminal being directly welded to said third layer and a second current terminal being directly welded to said third layer whereby electric current passes from the first terminal through said third layer to the second terminal.
Claim 3
Dependent Claim
29 words
The thermionic cathode as claimed in claim 1, wherein thermoelectron emissive compound has a general formula of MeB 6 wherein Me represents alkali earth metal or rare earth metal.
Claim 4
Dependent Claim
23 words
The thermionic cathode as claimed in claim 2, wherein the alkali earth metal is selected from the group consisting of barium and calcium.
Claim 5
Dependent Claim
15 words
The thermionic cathode as claimed in claim 3, wherein the alkali earth metal is barium.
Claim 6
Dependent Claim
25 words
The thermionic cathode as claimed in claim 2, wherein the rare earth metal is selected from the group consisting of lanthanum, yttrium, samarium and gadolinium.
Claim 7
Dependent Claim
15 words
The thermionic cathode as claimed in claim 5, wherein the rare earth metal is lanthanum.
Claim 8
Dependent Claim
27 words
The thermionic cathode as claimed in claim 1, wherein the metal of high melting point is selected from the group consisting of tantalum, tangusten, molybdenum and rhenium.
Claim 9
Dependent Claim
52 words
The thermionic cathode as claimed in claim 1, wherein the reaction barrier material is selected from one or more of the group consisting of zirconium boride (ZrB 2 ) , titanium boride (TiB 2 ), tantalum boride (TaB 2 ), niobium boride (NbB 2 ), zirconium nitride (ZrN) and tantalum nitride (TaN).
Claim 10
Dependent Claim
35 words
The thermionic cathode as claimed in claim 8, wherein the reaction barrier material is selected from one or more of the group consisting of zirconium boride (ZrB 2 ) and titanium boride (TiB 2 ).
References Cited (Backward Citations)
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Cited
US3440475A
Cited
US3745403A
Cited
US3823337A
Cited
US3928783A
Cited
US4055780A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-01-29 | 1982-07-31 | 1983-01-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-01-29 | 1986-07-31 | 1987-01-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-01-29 | 1990-07-31 | 1991-01-30 | $7700.00 | Window Closed / Lapsed |